In existing synthesis communications, when a first user equipment (UE for short) uploads and downloads various kinds of data by means of a data communications service that is provided by a mobile communications system, reliability or a throughput rate of data transmission is sharply reduced due to deterioration of an environment of the first UE itself. Therefore, an access network device, such as an eNB that is a base station, may first send, to a current supporting UE of the first UE, data that is to be sent to the first UE, and then the current supporting UE forwards the data to the first UE by using a short-range communications technology between the current supporting UE and the first UE, so as to achieve an effect of multiuser diversity.
However, in the existing synthesis communications, after the access network device establishes a cooperative relationship between the first UE and the current supporting UE, when a status of a short-range link between the current supporting UE and the first UE becomes poor or a status of a macro network link between the current supporting UE and the access network device becomes poor, the reliability or the throughput rate of data transmission for the first UE is sharply reduced because a cooperative communication relationship between the first UE and the current supporting UE cannot be updated in the existing synthesis communications.